This invention relates to a suspension for a truck or trailer, and more particularly, the invention relates to a suspension stabilization device for a truck or trailer.
Trucks having trailers or cargo containers frequently unload their cargo onto a loading dock. The vehicle is backed into the dock loading and unloading area so that lift trucks and other cargo carrying devices may enter the cargo area of the vehicle trailer. As the lift trucks load and unload the cargo of the vehicle, the angle of the cargo floor may change dramatically as a result of the load being shifted. As a result, it may be unsafe for the operator and difficult if not impossible for the lift truck to navigate its way through the cargo area and into and out of the dock area.
Active ride suspension systems are frequently used to maintain the ride height of the vehicle trailer when the vehicle travels along a roadway. The active suspension system includes inner springs which are inflated and deflated to raise or lower the trailer relative to the axle to maintain ride height. Active ride suspension systems are unsuitable to maintain dock height because the response time of the system is insufficient to adjust the air springs to accommodate the shift in trailer height as the weight of the cargo is shifted in the cargo area of the trailer. That is, the air springs simply may not be inflated or deflated rapidly enough to adjust the height of the cargo area relative to the suspension. Therefore, what is needed is a mechanism to maintain the dock height of the trailer cargo area relative to the dock area during unloading and loading of cargo.
The present invention provides a dock height hold device for a vehicle including a frame supporting a cargo area. A suspension is pivotally connected to the frame and supports an axle. Air springs, which are typically a part of an active ride suspension system, are arranged between the frame and suspension to maintain a ride height between the frame and suspension between vehicle travel. According to the present invention, a pedestal preferably is supported on the suspension. The pedestal is rotatably movable between a hold position in which the pedestal extends from the suspension to a location proximate to the frame and a retracted position in which the pedestal is further from the frame than when in the hold position. An actuator, which is presently mounted between a portion of the suspension and the pedestal, moves the pedestal between the hold and retracted positions for maintaining a desired space in between the suspension and the frame in the hold position. The air springs typically maintain a sufficient space between the frame and the suspension such that the pedestal may be rotated uninhibited into the hold position. In the hold position, there is preferably approximately a xc2xe inch clearance between the pedestal and the frame. As a result, the cargo area is permitted to shift an insignificant amount, limited to xc2xe inch, during shifts of cargo in the cargo area of the trailer.
Accordingly, the above invention provides a mechanism to maintain the dock height of the trailer cargo area relative to the dock area during unloading and loading of cargo.